Dr Racaniello said
Not at all he said, PCR is the gold standard for diagnosing viral infections. When you think you have flu, your doc gives you a rapid test in the office. Those are antigen-based and are lousy. If the answer is negative, you go to PCR.
he missed the point.
Flu is actually a good example of the problems of PCR. It doesn't show up in blood, you have to look at respiratory secretions.
PCR works well if you know which probes and primers to use and if you actually have some of the virus in your sample, but that means you have to know which tissue to use and how to treat your sample to maximise your chance of getting a virus in it.
They have been trying to get PCR to work with some bugs for years.
It is not a "gold standard" for proving virus is there - photographing the virus, as Elaine De Freitas did, is the real proof and antibodies can be found even if the virus can't be isolated. What PCR does have is it is modern and "cool" as well as being automated (so cheaper). Diagnostic microbiologists are often mocked because their techniques have not changed much since the nineteenth century, they still grow bacteria on agar plates for instance. Virology, though, has come on in leaps and bounds and PCR is a chance to join in the biological revolution so it's advantages are often overstated.
It is also not a "gold standard " for diagnosing viral infections. The older methods of detection, even growing samples on eggs, showed that a virus was
there. You might not know what was killing the tissue culture but you knew something was. Now you could diagnose the patient as having a viral infection. Exactly what virus it was needed more thought, but you knew they were ill. Hepatitis non A non B led on to the discovery of the Hepatitis C virus but that can't happen using PCR as even when it works wonderfully it can only find what you already know all about and have a test for. Combine this with the modern tendency to assume psychological illness if a simple set of tests are negative and our horrendous situation can only spread.
XMRV is not the only retrovirus which is hard to find. Many papers describe the problems of detecting animal ones using PCR. Amplification gives the best chance of finding anything. The WPI did this after using simple PCR and when the CDC came up negative they should have taken this simple step. It is the sort of thing a Phd student would be expected to do, never mind a major research organisation.
Mithriel